The objective of the proposed study is to test the hypothesis that by treating the highest risk group of patients (those with coronary artery disease, left ventricular ejection fractions <40, spontaneous nonsustained ventricular tachycardia and inducible sustained ventricular tachycardia) with antiarrhythmic therapy guided by electrophysiologic studies, the risk of sudden arrhythmic death and spontaneous sustained ventricular tachycardia can be reduced.